快速创建Collection<Integer>
时间: 2024-05-15 08:17:12 浏览: 6
你可以使用以下代码快速创建一个Collection<Integer>:
```java
Collection<Integer> collection = new ArrayList<>();
```
这里我们使用了Java中的ArrayList类来创建一个整数类型的集合。你可以通过添加元素来向集合中添加元素。
相关问题
Collection<Integer> 如何转换为 arrylist
可以使用ArrayList的构造函数来实现Collection<Integer>向ArrayList<Integer>的转换,示例代码如下:
```
Collection<Integer> collection = Arrays.asList(1, 2, 3, 4, 5);
List<Integer> arrayList = new ArrayList<>(collection);
```
这样就可以将collection转换为ArrayList类型的arrayList了。注意,如果Collection中的元素类型不是Integer,需要进行相应的类型转换。
ArrayList<Integer>
An ArrayList is a class in Java that provides a dynamic array implementation. It is part of the Java Collections Framework and is used to store a collection of objects. The ArrayList class is a generic class that can be used to store objects of any type.
The ArrayList<Integer> denotes an ArrayList that can only store objects of the Integer type. This is achieved through the use of Java generics, which allows the type of objects stored in a collection to be specified at compile time.
Here's an example of how to create an ArrayList<Integer>:
```
ArrayList<Integer> myList = new ArrayList<Integer>();
```
This creates a new ArrayList that can store objects of the Integer type. The ArrayList is initially empty, and elements can be added using the `add()` method:
```
myList.add(1);
myList.add(2);
myList.add(3);
```
This adds the integers 1, 2, and 3 to the ArrayList. The `size()` method can be used to get the number of elements in the ArrayList:
```
int size = myList.size(); // size is now 3
```
Elements can be retrieved from the ArrayList using the `get()` method:
```
int element = myList.get(0); // element is now 1
```
This retrieves the first element in the ArrayList (at index 0) and stores it in the `element` variable.